%%
%% The LaTeX Companion, 3ed
%%
%% Example 16-7-24 on page II-557 in "Document divisions".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.0pt}

%  Use biber program
\makeatletter
\renewcommand\section{\@startsection{section}{1}{\z@}%
  {-1.75ex \@plus-1ex \@minus-.2ex}%           % bigger than in most examples
  {.5ex}%
  {\normalfont\large\bfseries}}
\renewcommand\subsection{\@startsection{section}{1}{\z@}%
  {-0.75ex \@plus-1ex \@minus-.2ex}%
  {.5ex}%
  {\normalfont\normalsize\bfseries}}

\makeatother
\setlength\parindent{0pt}

%StartShownPreambleCommands
\usepackage[style=authoryear]{biblatex}
\addbibresource{tlc-ex.bib}
\defbibheading{subbibliography}{%
  \subsection*{References for Article
               \ref{refsection:\therefsection}}}

%StopShownPreambleCommands

\begin{document}
\section{Article}          \newrefsection
\ldots\ \cite{smith2020-1} \ldots

\section{Another article}  \newrefsection
\ldots\ \cite{smith2020-2} \ldots

\printbibheading
\bibbysection[heading=subbibliography]
\end{document}
